Controlling wrinkles on the surface of a dielectric elastomer balloon

When a dielectric elastomer membrane is pre-stretched, inflated and then electromechanically activated, wrinkles may nucleate and propagate. Nucleation site, critical voltage and type of wrinkles can be tuned by controlling the initial pre-stretch, initial inflation pressure and applied voltage. We conduct a hybrid experimental and analytical study to investigate the role of these various parameters on the nucleation and propagation of wrinkles on the surface of an inflated dielectric elastomer balloon. Our results show that pre-stretching the membrane before inflation affects considerably types of wrinkles and their nucleation sites. While wrinkles are more spread throughout the surface of a slightly pre-stretched membrane, they are localized either near the clamped edge or the apex of the inflated balloon with initial large pre-stretch. We also discuss and analyze snap-through instability and electrical breakdown of the activated membrane. A three-dimensional phase diagram that delineates the different operation conditions of the activated dielectric elastomer membrane is constructed to aid designing soft actuators. (C) 2016 Elsevier Ltd. All rights reserved.